Oh your poor wife, and you as well.
Firstly, I would get a second opinion on the restitching. I had a couple of episiotomy stitches come out (looked horrific but nothing like what you describe), and put off pushing for a referral back to the consultant. Saw consultant at about 6 months and he could not understand why I hadn't come back straight away, said restitching was relatively simple. Of course, you'll have to be infection free first, but perhaps there is no need to suffer for months after that.
Secondly, it is painful, but it does heal up after a fashion, so even if a repair can't be done for months, that does not necessarily mean months of the pain your wife is in now.
Thirdly, for healing, I would recommend a bath twice a day, with lavender in. You can also get other healing herbs from eg neals yard (ask my midwife andrea dombrowe Surrey independent midwives for which herbs if you are interested). I did this, seemed to heal well (the initial healing, not the wound coming together obviously). I wouldn't apply anything else at all, or have showers etc, as all can introduce infection. In this weather, wearing a skirt and no knickers should help get air to the wound as well.
Also, sounds ridiculous, but she does need to try to keep her legs together as much as possible. An epi wound will open up each time legs are moved apart, so need to try not to sit cross legged etc.
Fourth, re the bf and anti bs, your wife needs to keep expressing every 3 hours if she wants to bf when she is off the anti bs. It would be a shame to muck up the bf for the sake of this, if she is keen on bf that is, it just makes this even more traumatic.
Fifth, it is not your fault. It is not her fault. It is possibly the hospitals fault, but then again, sometimes this crap just happens. I've had 2 awful births, both times I think the hospital were to blame, but really, they were just trying to prevent a worse outcome. What I'm trying to say is that beating yourself up will not help. The hospital probably has a post birth reflections/counselling service you can go to in the fullness of time. Use it, it will help. But in the meantime, put blame out if your head and focus on your baby and your wife.
Sixth, congratulations! This will get better, it's a hard start, but it will get better. Good luck.